Exemplary embodiments of this invention generally relate to environmental control systems of an aircraft and, more particularly, to an air-liquid heat exchanger assembly of an environmental control system.
Commercial jet aircrafts typically include environmental control systems (ECS) that regulate air supply, temperature, and cabin pressurization on the aircraft. Such an ECS may also be utilized to cool components of the aircraft itself, such as electrical systems. The ECS of most jet aircrafts typically includes two or more ECS packs which provide pressurized air of an appropriate temperature to the cabin of the aircraft by utilizing heated, pressurized bleed air from the engines or auxiliary power unit of the aircraft, as well ambient ram air that enters the aircraft through a ram scoop.
An ECS pack includes an air cycle machine fluidly connected to one or more air-liquid heat exchangers. At least one of the air-liquid heat exchangers is used to increase the temperature of the air, and decrease the temperature of the liquid so that both may be provided at a correct temperature to downstream loads. Some known ECS systems include a bypass valve positioned upstream of the entire air-liquid heat exchanger to allow the liquid to bypass the entire heat exchanger assembly to attain a desired downstream mix temperature. As a result, portions of the air-liquid heat exchanger cold air circuit may freeze or portions thereof may deviate from adequate operating conditions.